1. Field of the Invention
The invention relates in general to elevator systems, and more specifically to elevator systems in which the elevator car is mounted for movement adjacent the external wall of a building.
2. Description of the Prior Art
Certain types of elevator installations require that the opening between the car and entranceway to a floor, necessary to provide running clearance between the elevator car and associated hoistway wall, be sealed when the car door is opened. For example, U.S. Pat. Nos. 1,021,172 and 1,406,951 are directed to elevator constructions suitable for cold storage warehouses, which construction prevents cold air from a floor from excaping into the elevator shaft when the elevator car and hoistway doors are opened.
U.S. Pat. No. 1,021,172 discloses a rectangular frame carried by the elevator car which is manually projected via a lever arrangement to contact the hoistway wall. The lever, when operated to advance the frame, opens a switch in the drive motor circuit to prevent the elevator car from being operated until the frame is retracted and the switch is closed.
U.S. Pat. No. 1,406,951 discloses an automatic sealing arrangement which requires that the wall about each hoistway door be modified to include elements which cooperate with elements carried by the elevator car to effect the desired seal. The sides of the car are continuously sealed to the hoistway wall by vertically oriented rails fixed on either side of the hoistway openings which extend the length of the hoistway, each of which cooperate with a pair of spaced flexible strips carried by the elevator car which are biased against opposite sides of the associated rail. Horizontally extending cross members are fastened to the hoistway wall above and below each door opening. These cross members have a convex cross-sectional configuration and they cooperate with flexible strips mounted across the top and bottom of the elevator car to automatically provide upper and lower seals when the elevator car is in registry with the hoistway door. The elements of the side seals are in continuous sliding contact, and the elements of the top and bottom seals contact one another as the car passes each hoistway door, whether or not the elevator car stops at the associated hoistway door.
In recent years, elevators have been constructed to operate along an exterior wall of a building, and the normal running clearance provides a space for precipitation and wind to enter the elevator car and adjacent floor when the elevator car and hoistway doors are opened. U.S. Pat. No. 3,734,238 discloses an arrangement which requires that the exterior wall of the building be modified to include elements which cooperate with elements carried by the elevator car to provide a wind and rain shield or seal. Vertically oriented U-shaped elements are fixed to the exterior building wall, on each side of the hoistway openings, which cooperate with W-shaped members carried by the elevator car on each side of its door opening, to provide lateral seals. Magnetic plates are fastened to the exterior wall, above and below each hoistway opeing. Magnetic gaskets disposed above and below the elevator car door are electromagnetically retracted until the car stops and ceases leveling. Electromagnets are then de-energized and springs drive the magnetic gaskets against the magnetic plates to effect the upper and lower seals. Micro-switches operated by the retractable upper and lower seals prevent operation of the elevator car when the upper and lower seals are in their extended positions.
While these prior art arrangements provide effective seals, it would be desirable to provide such a seal between an elevator car and the exterior wall of the building without requiring modification of the exterior wall, without requiring sliding components subject to wear, and without any auxiliary electrical circuits or auxiliary electrical interlocks. It would also be desirable to automatically provide such a seal only when the seal is necessary, i.e., when the elevator car is stopped and the car and hoistway doors are open to permit passanger transfer.